It has been one and half centuries since the first jeans' birth in 1873. Jeans are working suits designed for Americans to deal with heavy daily work in the nineteenth century. After persistent development, jeans have become fashionable clothing and are popular all over the world. Now, denim products are not just limited to jeans. Denim clothing has a diversified development and the market thereof is growing. Since denim fabrics and clothes are suitable for all ages to wear and have high universality, they are fashionable clothes adored by consumers.
When denim clothes emerged in China, millions of Chinese consumers liked to wear denim clothes despite the seasons. According to incomplete statistics, denim fabrics produced in China every year have reached 2 billion meters, accounting for ¼ of the world production. Moreover, denim clothes produced in China every year are over 2.5 billion. China has become an important producing country of denim fabrics in the world.
However, as everyone knows, each piece of jeans is produced from cotton to finally become a fashionable and beautiful jeans clothing product through spinning, dyeing, weaving, finishing, garment forming and washing with water. Wherein, the spinning process is a key for product quality. Ring spinning is adopted generally in the existing technology, and conventional ring spinning refers to processes of rotatably introducing fiber slivers obtained after drafting of rough yarns through a ring-spinning steel wire ring and twisting cotton yarns into spun yarns. The winding speed of a bobbin is faster than that of the steel wire ring. Yarns are characterized by presenting conical helixes transferred inwards and outwards, wherein fibers are wound and connected inwards and outwards in the yarns, and thus the yarns are compact in structure and are strong. However, the conventional ring spinning process has the characteristic that the twist triangulation space is too long that a certain residual torque is formed by single yarns, which gives rise to larger biasfilling of the final fabric, and in case of poor control, a distortion situation will be formed in garment washing. Therefore, the wearing comfort level is reduced. In the traditional process, in order to improve such situation, the twisting degree of the yarns will be reduced generally. However, there will be certain limitations, such as reduction of spinnability, quality reduction of products and the like.
In the dyeing process, synthesized indigo dyes are used generally, and are substituted by sulfur dyestuff having similar firmness and performances due to single color, complicated production procedures and high cost. If containing previous powdered solid sulfur dyestuff, the sulfur dyestuff can be applied just by boiling and dissolving with sodium sulfide. However, sulfur dioxide gas will be released in this process, and the production process is not environment-friendly. The liquid sulfur dyestuff contains a certain amount of sodium sulfide reducing agent per se and shows a pre-reduced leuco compound form. But, relatively speaking, the sulfide content is relatively high, the purity of the dyestuff is low and is not easy to be oxidized, and thus the water consumption in production is high.
In the finishing process, a liquid ammonia mercerizing finish technology or an alkali mercerizing process will be applied. A method for removing ammonia by using steaming and washing with water in the traditional liquid ammonia mercerizing finish technology will produce a large amount of wastewater. A large amount of water needs to be consumed and a large amount of waste alkali is drained in the conventional alkali mercerizing process. Thus, the COD content in wastewater is high.
It can thus be seen that the production in each process aforementioned will generate different levels of energy source consumption, and especially the consumption of water resources by the denim fabrics acting as printing and dyeing products is most obvious. It is shown by data that 17980 liters of water needs to be consumed in the dyeing process of every 1000 pieces of jeans. Fresh water resources are lacking on the earth, and fresh water only accounts for 2.6% of the total water on the earth, including glacier, underground water and the like. Fresh water resources that can be used by human beings are actually very limited. Therefore, it is an urgent problem to be solved to produce the environment-friendly denim fabric in the industry while the product quality is ensured.